1. Field of the Invention
The present invention relates to low-calorie food products, such as meringues and mayonnaise-like foods, which contain konjak mannan and processes for preparing the same.
2. Discussion of the Background
Low-calorie versions of foods are becoming increasingly important as society becomes more aware of the relationship between diet and health. In particular, low-calorie versions of normally high-calorie foods, such as meringue and mayonnaise, are desirable.
Meringue, which is a material for foods such as sponge cakes, etc., utilizes the foaming properties of egg white, but in order to obtain good quality meringue, the use of sugar is regarded as essential. The reason is that by the addition of sugar to egg white, more minute and more stable foams are formed than the case of egg white alone.
However, in general, the amount of sugar added to the egg white solution is quite high, such as 50-100 g per 100 g of the egg white solution, and the resulting meringue and sponge cakes utilizing it are inevitably high in calories.
Therefore, various thickening stabilizers for the purpose of replacing the function of sugar in meringue have been studied, among which konjak mannan is known to have an effect to improve the qualities of meringue.
Konjak mannan is a hardly digestible polysaccharide obtained from the roots of konjak, a plant belonging to the taro family, and is believed to have physiological functions of a food fiber such as the prevention of constipation, lowering of the blood cholesterol etc., and konjak mannan aqueous solutions exhibit remarkable thickening properties like various polysaccharides. Therefore, there have been various studies of the use konjak mannan as a thickening stabilizer for various foods, and konjak mannan has been used for the prevention of the deformation of meringue or as a replacement for sugar (Japanese Patent Application Laid-open No. 28237/1983 and Japanese Patent Application Laid-open No. 17950/1984), and specifically, meringue is produced by adding and mixing a solution of konjak mannan at the time of whipping the egg white.
However, when konjak mannan is used in meringue by the above-described conventional methods, it has been found that the following serious drawbacks are encountered:
(1) The konjak mannan powder is poor in solubility, and therefore when meringue is produced by adding it to an egg white solution, most of the konjak mannan particles added cannot be dissolved and thus remain in the meringue as undissolved particles.
(2) When konjak mannan is dissolved in water beforehand and added to an egg white solution, it is possible to dissolve into the egg white solution under conditions where the concentration of the konjak mannan aqueous solution is 1% or less, but with the addition of about 10 g of the 1% konjak mannan aqueous solution based on 100 g of the egg white solution, a satisfactory effect to form and stabilize the merinque cannot be achieved. Further, if the amount of the konjak mannan aqueous solution added is increased, the egg solution itself is diluted with water as a result, and thus the resulting meringue and sponge cakes utilizing it are watery and have poor texture.
(3) In the case of a konjak mannan aqueous solution having a concentration of more than 1%, since it exhibits very high viscosity and has physical properties like a jelly, when added to an egg white solution, it forms lumps and cannot be dissolved.
Further, if dissolution operations such as stirring etc. are vigorously conducted, the egg white solution starts to foam and as a result, undissolved jelly-like konjak mannan remains in meringue, resulting in remarkable deterioration of the quality of the meringue and also the sponge cakes utilizing it.
Therefore, it is difficult to utilize konjak mannan and obtain good quality meringue by the prior art methods, and thus there remains a need for a process of preparing konjak mannan containing meringues efficiently which does not result in undissolved konjak mannan remaining in the merinque.
Mayonnaise, as is well known, is an O/W type emulsified product consisting of an oil phase and an aqueous phase, which has characteristic smooth texture as well as viscosity and thickness. In other words, in mayonnaise, oil is essential for forming the characteristic texture of mayonnaise. However, in general, the oil content in mayonnaise usually accounts for 70% by weight or so, and as a result, mayonnaise inevitably is very high in calories.
Therefore, applications of konjak mannan to mayonnaise have been previously studied. In Japanese Patent Application Laid-open No. 28237/1983, it is disclosed that the products are stabilized and concentrated by adding konjak mannan to mayonnaise. Further, in Japanese Patent Application Laid-open No. 122748/1982, a mayonnaise-like food in which the calorie content has been lowered by adding a konjak gel or sol is disclosed.
Further, the application of a gelatinized starch paste, which is a thermally gelatinized product of starch, for the purpose of aseptically producing a low acidity type mayonnaise is disclosed in Japanese Patent Publication No. 12706/1981.
However, a sol of konjak mannan exhibits remarkable thickening properties and viscoelasticity.
Therefore, in the production of mayonnaise, especially a mayonnaise-like food in which the oil content has been lowered, when konjak mannan is applied for the purpose of imparting the viscosity and thickness and, in addition, stabilizing the emulsion, a characteristic viscoelasticity is manifested in the product, thus only producing mayonnaise of very unfavorable qualities.
Further, when only the gelatinized starch paste is used, the emulsion of the product is partially broken and syneresis occurs, and the product feels powdery in the mouth, and thus it is impossible to obtain a mayonnaise of good qualities.
Thus, there remains a need for a mayonnaise-like food which does not differ from ordinary mayonnaise food in quality and a process for the production of a mayonnaise-like food which utilizes konjak mannan and in which the oil content has been lowered.